A solitary sunfish at an aquarium in southwestern Japan lost its appetite, began banging into the side of the fish tank, and appeared unwell days after the facility closed last month for renovations.

This may sound like the start of a particularly silly joke, but it was a very real challenge faced by staff at a Japanese aquarium when they noticed their sunfish was ailing. Almost as soon as the ...

A solitary sunfish at an aquarium in southwestern Japan lost its appetite, began banging into the side of the fish tank and appeared unwell days after the facility closed last month for renovations.

When the sunfish began looking unwell days after the aquarium closed on Dec. 1 for a six-month renovation, its keepers suspected digestive problems, gave it less food and visited the fish tank to ...